Security readout for executives and security teams
Plain-English summary
CVE-2021-40452 is a high-severity Microsoft HEVC Video Extensions remote code execution flaw. A user must interact with malicious content, so the main business risk is endpoint compromise through media-handling workflows. The sources do not name affected versions or a specific KB, so remediation should follow Microsoft’s CVE guidance directly.
Executive priority
Treat as a high-priority endpoint patching item, especially for users who handle external media. It is not described as actively exploited in the supplied sources, but the potential impact is full compromise of affected endpoints after user interaction.
Technical view
The CVSS 3.1 vector is 7.8 high: local attack vector, low complexity, no privileges required, user interaction required, unchanged scope, and high confidentiality, integrity, and availability impact. The affected product is Microsoft HEVC Video Extensions. The public bundle does not include CWE mapping, affected version ranges, or proof-of-concept details.
Likely exposure
Exposure is most likely on endpoints where Microsoft HEVC Video Extensions is installed and users can open or preview untrusted HEVC media. The source bundle lists versions as N/A and provides no CPEs, so asset validation must rely on installed software inventory and Microsoft advisory checks.
Exploitation context
The provided data does not support active exploitation. CISA KEV is false in the bundle, and CVSS exploit code maturity is listed as unproven. The vulnerability still matters because no privileges are required and successful exploitation could produce full security impact after user interaction.
Researcher notes
Public metadata is sparse. The CVE record confirms product, severity, vector, and MSRC reference, but not affected versions, root cause, CWE, exploitability details, or exact fix identifiers. Avoid assumptions beyond Microsoft HEVC Video Extensions and validate directly against MSRC data.
Mitigation direction
- Follow Microsoft MSRC guidance for CVE-2021-40452 and apply available remediation.
- Inventory endpoints for Microsoft HEVC Video Extensions presence and update status.
- Prioritize systems used to handle external or untrusted media files.
- Restrict opening untrusted HEVC media until remediation is confirmed.
- Monitor Microsoft guidance for version-specific or deployment-specific instructions.
Validation and detection
- Confirm whether Microsoft HEVC Video Extensions is installed on managed endpoints.
- Compare installed versions or remediation state against Microsoft’s CVE-2021-40452 advisory.
- Verify patch deployment through endpoint management or software inventory records.
- Check whether high-risk user groups process external HEVC media.
- Document any systems where version exposure cannot be determined.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-40452 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40452CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.